Electrical measuring instrument.



No. 698,681. Patented Apr. 29, I902.

T. DUNCAN. ELECTRICAL MEASURING INSTRUMENT.

(Application filed Jan. 2, 1900. Renewed Jan. 6, 1902.) (No Model.) 2 Sheets-Sheet I.

1' "cams PETERS co. mo'ro umofl WASHINGTON. n. c.

No. 698,68I. Patented Apr; 29, I902.

T. DUNCAN.

ELECTRICAL MEASURING INSTRUMENT.

(Application filed Jan. 2, 1900. Renewed Jan. 6, 1902.) v (No Model.) 2 Sheets-Sheet 2.

\A/LIITEEE E5 InV EntuL Q EX%%W UNITED STATES PATEN OFFICE.

THOMAS DUNCAN, OF CHICAGO, ILLINOIS, ASSIGNOR TO THE SIEMENS & I-IALSKE ELECTRIC COMPANY OF AMERICA, OF CHICAGO, ILLINOIS, A

CORPORATION OF ILLINOIS.

ELECTRICAL MEASURING INSTRUMENT.

SEECIEIOATION forming part of Letters Patent No. 698,681, dated April 29, 1902.

Application filed January 2,1900. Renewed January 6, 1902. Serial No. 88,489. (No model.) I

To (06L whom it may concern.-

Be it known that I, THOMAS DUNCAN, a citizen of the United States, residing at Chicago, in the county of Cook and State of Illinois, have invented a certain new and useful Improvement in Electrical Measuring Instruments, (Case No. 343,) of which the following isafull, clear, concise, and exactdescription, reference being had to the accompanying drawings, forming a part of this specification.

My invention relates to voltmeters, and has for its object to provide an instrument that will measure the pressure across the generator-terminals, the drop in pressure or the c 1' drop over aservice or transmission conductor, and the pressure at any predetermined point in the transmission-circuitas the center of distribution, for example.

hen the pressure at any point distant from the generating-station is accurately de-.

C R drop over the distributing-lines due there to, which varies directly as the load.

Two ways have hitherto been frequently practiced for measuring the pressure at a predetermined point in the line distant from the generating-station. ploy an ordinary voltmeter upon the stationswitchboard which is connected at a distant point-as, for example, the center of distributionby means of two pressure-wires, the instrument then indicating the pressure at the distant point. When the distance between the distant predetermined pointof the line and the generating-station is great, the expense of these pressure-wires is significant when a great number of machines are used. It has also been the practice to employ what are termed compound compensating Voltmeters containing two windings, one a pressure-winding connected between the generator-terminals and the other a counter compounding or demagnetizing winding comprising one or more turns of the series or main conductor upon the same voltmeter-spool with the shunt-winding, the current increas ing the counter magnetizing eiTect of the se A common way is to emshaft upon a suitable measuring-scale.

ries winding as the load increases to give a resultant magnetizing effect which indicates the pressure reduction in the transmission line. The number of turns of'the current or series windingis dependent upon the percentage of drop in the mains. This latter method, however, is objectionable, since a true compensation is not always effected in the meter for the C R drop, since the counter magnetizing effectof the series winding would be the same irrespective of the distance of the load from the generator.

In my application Serial No. 87, filed of even date herewith, I have disclosed an apparatus for accurately measuring the pressure at a distant point in which a pointer and a scale were associated with each of the windings, whereby the C R drop and the pressure at the generator terminals could be separately measured. \Vith the apparatus disclosed in the said application in order to ascertain the difference in potential at the predetermined distant point twice the C Rdrop in one transmission-conductor or a portion thereof was subtracted from the indicated pressure at the generator-terminals, the portion of the apparatus for measuring the c 7" drop in one transmission-line or portion thereof being so calibrated as to indicate directly the total C R drop, so that it was only necessary to take the dilference between the amounts to determine the pressure at the predetermined distant point.

In my applicationSerial No. 88, filed of even date herewith, I have shown an instrument capable of giving the pressure at any predetermined point of atransmission-line in a single reading.

To effect this result, I preferably caused said windings to effect a single movement proportional to the pressure at the said distant point of the system, the said windings jointly creating a single torque and being mounted upon a common oscillating shaft having a pointer movable therewith, which was adapted to indicate the movement of the The resultant of the said torques was proportional to the algebraic sum of the pressure across the generator-terminals and the O R drop, l the latter coilbeing preferably mounted upon the torques due to the meter-windings acting in opposite directions. By means of my present invention I am enabled to measure the pressure at the generator-terminals, the pressure at a distant point in the transmission system, and the O R drop, although an instrument may be constructed embodying features of my invention which may be limited to the measurement of a lesser number.

of load conditions.

In practicing my invention I preferably construct the meter somewhat similarly to that disclosed in my last aforesaid application, and in order to carry out the objects of the presentinvention Iprovide means whereby there may be an independent action of one or either winding irrespective of the other. I preferably employ switching mechanism to control the action of either or both windings with the transmission-circuit.

I will describe my invention more particularly by reference to the accompanying drawings, in which Figure 1 diagrammatically illustrates an instrument constructed in accordance with my invention and a system of distribution with which the said instrument is connected. Fig. 2 is a plan view of a single key-actuating device by the actuation whereof either one of two keys, or both, may be actuated. Fig. 3 is a longitudinal elevation of the device shown in Fig. 2. Fig. 4 1s an end elevation thereof.

Like parts are indicated by similar letters of reference in all of the views.

I have indicated a system for distributing direct current, a source of direct current a being shown as supplying current to translating devices I). The instrument 0 may be constructed as shown, two field-poles cl e of soft iron being preferably provided, a permanent horseshoe-magnetf being preferably employed, upon the ends of which the said.

pole-pieces are secured. An iron core 9, which is preferably stationary, is disposed between the poles. A coil h of fine wire, mounted upon a rotatable shaft, surrounds the iron core and is disposed between the pole-pieces, this coil being adapted for inclusion in circuit between the generator-terminals, preferably by means of a key '6, normally maintaining the conductor including the said coil open, a resistance is, extraneous to the said coil, being adapted for inclusion in the same cross-conductor with said coil or winding to prevent waste of current through said coil. A torque is thus produced proportional to the pressure impressed by the generator upon the transmission-mains. Torsional springs may be provided in the wellknown way to oppose this torque.

I have shown a pointer Z, mounted to swing with the coil, and a scale m, upon which the movements may be read.

A second coil n is mechanically coupled with the aforesaid coil,

the same shaft with the coil h. The coil 'n may be included between the separated points 0 and p, in this instance the generator-terminal and a distant point of the distribution system, respectively, an extraneous resistance q being preferably adapted for inclusion in the same circuit with the said coil. shown a metallic pressure-conductor r for connecting the points 0 and p. A part of this pressure-conductor may be replaced by the ground connections 8. p

I preferably employ a key or switch 25 for opening and closing the circuitincluding the coil or. The point 19 may be at the center of distribution or at the extreme end of the system of distribution, or a point between the extreme end and the center of distribution, or atany other point distant from the generating-station where it is desired to ascertain the pressure.

The winding h may, for example, exert a.-

torque which will rotate the pointer Z in a clockwise direction when the key 1'- is closed. The coil 91 causes a torque to effect the movement of the pointer inan opposite direction. The pointer is shown as resting at zero. To ascertain the generator-pressure, the key 'iis closed, the pointer swinging to'the right to effect the indication, the keyt being open. To measure the (J R drop, the keyi is released and the key t closed to effect the desired measurement, the pointer moving in the reversed direction. If it should be desired to ascertain thepressure at the pointp, both keys 7; and t are closed, the coil 71 creating a torque in opposition to that produced by the coil It, assuming that there is a load upon the system.

I preferably so adjust the windings of the instrument that the winding receiving its on rrent from conductor 1* will produce relatively twice the torque for a given pressure impressed at its terminals than that caused by the winding subjected to the generator-pressure.

In Figs. 2, 3, and 4 I have shown a device by which either or both of the keys may be operated. The device consists of a centrallypivoted bar u, carrying a handle 1 by which it maybe rotated. The ends of the bar are enlarged laterally, the lateral enlargements extending from one longitudinal end of the bar. When the bar occupies a central position, both keys will be depressed. hen the bar is swung from its central position, one key or the other will be depressed, according to the direction of rotation, while the remaining key will be released. This device does not form a part of my present invention.

By means of the apparatus of my present invention I am enabled to determine the total energy given.out by the generator, which is the product of the current times the reading at the scale at when the key t is alone closed and the energy consumed in the line or main I have leads, which will be the product of the cur rent times the reading at the scale m when the key i is alone closed, or C R. The difference between these two prod ucts will indicate the amount of energy available for the translating devices. The resistance of the transmission mains or leads may also be ascertained by dividing the drop in volts determined by the instrument when the key If is alone closed by the current in amperes- In some of the claims I speak of the windclaim as new and desire to secure by Letters Patent 1. In a system of electrical distribution, the combination with a voltmeter provided with a single measuring element, of means for including the said meter in circuit to measure the pressure across the generator and to measure the c drop in the line, substantially as described. a

2. In a system of electrical distribution, the combination with a voltmeter provided with a single measuring element, of meansfor including the meter in circuit to measure the pressure across the generator-terminals and to measure the pressure at a point in the transmission system distant from the generator, substantially as described.

3. In a system of electrical distribution, the combination with a voltmeter provided with a single measuring element, of means for including the meter in circuit to measure the c 1' drop in the line and to measure the pressure at apoint in the transmission system distant from the generator, substantially as described.

4. In a system of electrical distribution, the combination with a voltmeter provided with a single measuring element,v of means for including said meter in circuit to measure the pressure across the generator,the pressure at a point distant from the generator, and the c r drop in the line, substantially as described. Y

5. In a system of electrical distribution, the combination with a voltmeter associated therewith and provided with a single measuring element, a meter-winding for determin-. ing the pressure at the generator-terminals, and a second meter-winding for determining the c r drop in the line, of means for rendering a meter-winding active or inactive, sub

stantially as described.

6. In a system of electrical distribution, 7

the combination with a voltmeter associated therewith and provided with a single measuring element, a meter-winding for determining the pressure at the generator-terminals, and a second meter-winding for determining the c '1" drop in the line, of means for rendering each meter-winding active or inactive, substantially as described. I i

7. In a system of electrical distribution,

the combination with a voltmeter associated therewith and provided with a single measuring element, a meter-winding fo'r'determining the pressure at the generator-terminals, and a second meter-winding for deter mining the c 1" drop in the line, of means for rendering each meter-winding active or in active and for rendering'both of said meterwindings simultaneously active to determine the pressure at apoint ot' the transmission- .circuit distant from the generator, substantially as described.

8. In a system of electrical distribution,

the combination of a voltmeter therewitlnprovided with a single measuring element and two pressure-windings, one for connection between the generator-terminals todetermine the generator-pressure, and the other for connection between a point at the generator and a distant point of the transmission-line to determine the c 4" drop in the line, substantially as described.

9. In a system of electrical distribution, the combination with a voltmeter'provided withasingle measuring element and two pressure-windings, one for inclusion in circuit to either winding into and out ofcir'cuit to determine either the generator-pressure one 0" drop and for switching both windings into circuit at the same time to determine the pressure at said distant point, substantially as described.

11. In a system of electrical distribution, the combination of a voltmeter therewith provided with a single measuring element and two pressure-windings, one forconnection between the generator-terminals to determine the generator-pressure and the other for con,- nection between a point at the generator and a distant point of the transmission-line to determine the c 1" drop in the line, and a rotatable shaft upon which said windings are mounted, substantially as described.

12. In a system of electrical distribution, the combination with a voltmeter provided withasingle measuring element and two pressure-windings, one for inclusion in circuit to determine the generator-pressure and the second for inclusion in circuit between a point near the generator and a distant point of the transmission-line, of means for switching a winding into and out of circuit, and'a rotatable shaft upon which said windings are mounted, substantially as described.

13. In a-system of electrical distribution, the combination with a voltmeter provided with a single measuring element and two pressure-windings, one for inclusion in circuit to determine the generator-pressure and the second for inclusion in circuit between a point near the generator and a distant point of the transmission line, of means for switching either winding into and out of circuit to determine either the generator-pressure or o 7" drop, and for switching both windings into circuit at the same time to determine the pressure at said distant point, and a rotatable shaft upon which said windings are mounted, substantially as described.

14:. In a system of electrical distribution, the combination of a voltmeter therewith provided witha single measuring element and two windings, one for connection between the generator-terminals to determine the generator-pressure, and the other for connection between a point at the generator and a distant point of the transmission-line to deter-' mine the c r drop in the line, the said windings serving to create opposing torques, substantially as described.

15. In a system of electrical distribution, the combination with a voltmeter provided with a single measuring element and two pressure-windings, one for inclusion in circuit to determine the generator-pressu re and the second for inclusion in circuit between a point near the generator and a distant point of the transmission-line, of means for switching a winding into and out of circuit, said windings serving to create opposing torques, substantially as described.

16. In a system of electrical distribution, the combination with a voltmeter provided with a single measuring element and two pressure-windings, one for inclusion in circuit to determine the generator-pressure and the second for inclusion in circuit between a point near the generator and a distant point of the transmission-line, of means for switching a winding into and out of circuit, said windings serving to create opposing torques, substantially as described.

. 17. In a direct-current system of electrical distribution, the combination with a directcurrent generator supplying the system of distribution, of a voltmeter provided with a single measuring element, and means for conmeeting the said meter conductively in circuit to measure the pressure across the generator and to measure the c r drop in the line, sub-, stantially as described.

18. In a direct-current system of electrical distribution, the combination with a directcurrent generatorsupplying the system of distribution, of a voltmeter provided with a single measuring element, and means for connecting the meter conductively in circuit to measure the pressure across the generator-terminals and to measure the pressure at a point in the transmission system distant from the generator, substantially as described.

19. In a direct-current system of electrical distribution, the combination with a directcurrentgeneratorsupplying the system ofdistribution, of a voltmeter provided with a single measuring element, and means for conmeeting the meter conductively in circuit to measure the c 0' drop in the line and to measure the pressure at a point in the transmission system distant from the generator, substantially as described.

20. In a direct-current system of electrical distribution, the combination with a directcurrent generator supplying the system of distribution, of a voltmeter provided with a single measuring element, and means for conmeeting said meter conductively in circuit to measure the pressure across the generator, the pressure at a distant point from the generator and the c 1' drop in the line, substantially as described.

In witness whereof I hereunto subscribe my name this 20th day of December, A. D. 1899.

THOMAS DUNCAN.

Witnesses:

WILLIAM F. MEYER, JAMES W. DALTON. 

